In this thesis we describe some manipulations and applications of entanglement and a few physical implementations of these processes. First, we describe some applications of entanglement to state preparation in quantum optics. For this, we concentrate on a specific system of a cavity mode coupled to a macroscopic movable mirror. Next, we use the same system to propose an experiment to probe the decoherence of a macroscopic object. Our proposal is a quantum optical version of Schrodinger's cat thought experiment (entanglement between a microscopic and macroscopic system). After this, we describe how to entangle many spatially separated particles by operations at a central exchange. This is done by generalizing the scheme of entanglement swapping to the multiparticle case. Next, we show how entanglement swapping can also be used for concentrating shared entanglement and how a measure of pure state entanglement remains conserved in this process.
After this, we connect dense coding (an application of entanglement) to the apparently unrelated process of entanglement distillation. In this context, we obtain bounds on the capacity of dense coding with mixed states in terms of the entanglement of these states. Finally, we propose a physical implementation of teleportation that uses cavity decays. This is a rare example of a decay mechanism being made to play a constructive role in quantum information processing.